Benefits from lighter rims?

[zakjames]

Did a quick search but couldn't find anything on this, but was wondering what sort of benefits or gains would be expected when changing from standard heavy XR6 rims to lighter ones?

Curious because all my rims came with very bad gutter rash when I bought the car and was thinking would I be better off getting another set of standards, having them repaired, or getting lighter ones?

Cheers guys.

[Sox]

Lighter rims equal less unsprung weight.
Less unsprung weight means your suspension has an easier time in keeping your wheels on the bitumen.

[zakjames]

but nothing like quicker acceleration?

[ratter]

will also help with acceleration and braking, but some of that will depend on what tyres you put on

[zakjames]

coolio. thanks again

[Mr Hardware]

and this is why you don't buy big rims!
rims heavy!
tyres light!

[svo supporter]

Originally Posted by Mr Hardware

and this is why you don't buy big rims!
rims heavy!
tyres light!

Not necessarily. I've struck 20" rims that are lighter than factory 17" stuff.


I have also struck some 15" car tyres that are heavier than 20" ones.

[Mr Hardware]

Oh, of course thats true svo supporter, but unless they're cheap chinese cracking knockoffs or specifically lightened wheels, they'll be in the absolute minority.

And it is highly likely that 15" tyres will be heavier than 20" ones, but nowhere near the difference they will need to make up for the increase in wheel weight.

[Ducati888]

On a road car? Why bother. Are you drag racing? Might be some benefit there.

Less unsprung weight is a valid point, but how much less exactly? Equal to the weight of the tool kit in the boot? Half a tank of fuel? Or maybe staying off MacDonalds & beer for a month or so? Yes these are sprung weights, but really, how much benefit can there truly be in a road car, unless you are drag racing off the lights?

[AMB]

I've weighted a few standard steel and alloy 15 inch rims with tyres on, they all come in very close to 18 kg. I weighed one lighter set that were 12 kg. So that's 6 kg saving per tyre, 24 kg all up.

[Mr Hardware]

Originally Posted by Ducati888

On a road car? Why bother. Are you drag racing? Might be some benefit there.

Less unsprung weight is a valid point, but how much less exactly? Equal to the weight of the tool kit in the boot? Half a tank of fuel? Or maybe staying off MacDonalds & beer for a month or so? Yes these are sprung weights, but really, how much benefit can there truly be in a road car, unless you are drag racing off the lights?

It's not so much about performance, but about things like fuel economy. On another forum i read about someone put concrete in someone else's tyres and this killed performance and trebled fuel consumption.
Oh and depending on who you speak to, dropping 1kg of unsprung weight is the same as shedding anywhere between 2 and 10kg of sprung weight.
So on a 'road car', yes it can have a significant difference. For example, an ROH Azzurros in 18x8 form weigh approx 13kg
where as ROH Snypers (for example) in 16x7 form weigh only half as much as azzurros do
So that's 6.5kg per corner, giving you a total unsprung weight loss of 26kg. Even if you say that you've got some extra tyre sidewall mass to take care of, lets say 20kg. Then according to the 'internet experts' that is the equivalent of somewhere between a 40kg and 200kg sprung weight loss. And also according to the internet experts, for every 10lbs of sprung weight loss does the same for you as gaining 1hp, roughly.
So even if we take the 40kg sprung weight figure, that's 88lbs, which apparently is equivalent to 8.8hp, which is about 6.5kw.

So say you buy an old XR6 and fit extractors and azzurros to it, those two mods probably end up cancelling themselves out, from a performance standpoint anyway.

Or so the figures would have you believe.

But at the end of the day if you're after a lithe car with max power to weight ratio then a falcon is the wrong place to start.

[Day-mow]

also lighter wheels that are specially lightened are normally stronger yeah?
in a track situation i think is where you would reap most benefits of lightened wheels. but i think they also look pretty sic

[svo supporter]

Originally Posted by Mr Hardware

Oh, of course thats true svo supporter, but unless they're cheap chinese cracking knockoffs or specifically lightened wheels, they'll be in the absolute minority.

And it is highly likely that 15" tyres will be heavier than 20" ones, but nowhere near the difference they will need to make up for the increase in wheel weight.

Cheap chinese rims are heavier than normal factory rims. Those things weigh a bloody tonne. You know, the lovely big bling bling chromies that the boy racers love.

As for tyres. Ever lifted a RFT? When you do, then comment on weight difference.

[zakjames]

Cheers for the big write up Hardware, learn something new everyday.

[Mr Hardware]

is that right svo
i try and stay away from cheap rims

and yeah rft's are stupid

[Day-mow]

Originally Posted by svo supporter

You know, the lovely big bling bling chromies that the boy racers love.

maybe commonwhore drivers. but most boy racers aka imports. have lightened rims
;)

[svo supporter]

Originally Posted by Day-mow

maybe commonwhore drivers. but most boy racers aka imports. have lightened rims
;)

Not just commonwhore drivers mate. I've seen them on Falcons, Toyotas, Nissans and Subarus just to name a few.


MR HARDWARE. RFT aren't such a bad idea. Just heavy as all hell.

[The Monty]

My 15's from and AU1 Farimont - 17.4kg
16 inch Clover leaves with 215/55 slicks - 16.0kg
16 inch standard BA rims - 20.7kg
17 inch BA XR6 MKI rims - 20.7kg
17 inch BA XR6 MKI rims - 20.7kg
20 inch Chinese chrome rims - 34kg

[blownv8au]

i got a shock when i got my convo pros. 15x12 with 325 drag radials by arm i reckon they weigh less than 10kgs, when cold they light up easier than my 215s big differance when they are warm though lol.
My cousin said to me no one would be able to steal them they would be to bloody heavy. I said na man i could juggle them they are that light. he said crap, you don't know how to juggle. He had me, cracked me up proper lol.

[Tucool]

Originally Posted by Mr Hardware

It's not so much about performance, but about things like fuel economy. On another forum i read about someone put concrete in someone else's tyres and this killed performance and trebled fuel consumption.
Oh and depending on who you speak to, dropping 1kg of unsprung weight is the same as shedding anywhere between 2 and 10kg of sprung weight.
So on a 'road car', yes it can have a significant difference. For example, an ROH Azzurros in 18x8 form weigh approx 13kg
where as ROH Snypers (for example) in 16x7 form weigh only half as much as azzurros do
So that's 6.5kg per corner, giving you a total unsprung weight loss of 26kg. Even if you say that you've got some extra tyre sidewall mass to take care of, lets say 20kg. Then according to the 'internet experts' that is the equivalent of somewhere between a 40kg and 200kg sprung weight loss. And also according to the internet experts, for every 10lbs of sprung weight loss does the same for you as gaining 1hp, roughly.
So even if we take the 40kg sprung weight figure, that's 88lbs, which apparently is equivalent to 8.8hp, which is about 6.5kw.

So say you buy an old XR6 and fit extractors and azzurros to it, those two mods probably end up cancelling themselves out, from a performance standpoint anyway.

Or so the figures would have you believe.

A great read,I've been pondering on this question for a few years as I run 18" steel mags all round.... I even bought matching rims for when I go to the drags ( I hate seeing crap rims at the drags ) so I've probably shoot myself in the foot with all that extra load

[zakjames]

I did a bit of reading, but still can't really grasp what a RFT is exactly?

[FreddyDUZ747]

I have very lightweight rims all round on my BA and the difference was noticeable the first time I rolled out the driveway.The rolling speed pickup in D and off the footbrake increased,the pulsing that my car had through the powersteer had almost but gone.Taking the car around say a 60kmh/r turn was noticeable in my favour compared to the XR8 rims(I now want them back)in regards to effort needed on initial turn in,maybe they aid more performance from the tyre???,up their with the swaybar mod imo.

They just happen to be for sale aswell.

[AMB]

Originally Posted by zakjames

I did a bit of reading, but still can't really grasp what a RFT is exactly?

Look here
http://en.wikipedia.org/wiki/Run-flat_tire

[atec77]

Originally Posted by zakjames

Did a quick search but couldn't find anything on this, but was wondering what sort of benefits or gains would be expected when changing from standard heavy XR6 rims to lighter ones?

Curious because all my rims came with very bad gutter rash when I bought the car and was thinking would I be better off getting another set of standards, having them repaired, or getting lighter ones?

Cheers guys.

You will notice sharper steering and it usually smooths the ride , if they are lighter I went from 16"to 18"rims in a good wheel and they were quite a lot lighter , steering was much better